Molecular characterization of two Drosophila guanylate cyclases expressed in the nervous system
Abstract
Many lines of evidence from electrophysiological and biochemical studies have indicated that the GC-cGMP pathway very likely participates in various invertebrate neuronal functions, including phototransduction. In order to assess the role of GC-cGMP signal transduction in invertebrate neuronal functions, we have attempted to isolate and characterize the components of the GC-cGMP pathway in the nervous system of Drosophila. The overall goal of my project has been the molecular identification and characterization of Drosophila GC homologs expressed in the nervous system, particularly in the photoreceptor. We have isolated, by interspecies hybridization, two classes of Drosophila cDNA each encoding a different guanylate cyclase (GC). One of them encodes an $\alpha$ subunit homolog of soluble GC, designated DGC$\alpha$1 and the other encodes a receptor-type GC, designated DrGC. $dgc\alpha$1 cDNA encodes a protein of 676 amino acids and maps to 99B. In situ hybridization to adult tissue sections showed that $dgc\alpha$1 mRNA is found mainly in the cell bodies of the optic lobe, central brain, and thoracic ganglia. The DGC$\alpha$1 protein was also localized primarily to the nervous system by immunocytochemical staining, consistent with results of in situ hybridization. However, no detectable expression of this protein was found in the retina. The other class of cDNA, drgc, maps to 76C and encodes a 1525 amino acid protein displaying structural features similar to other known receptor-type guanylate cyclases. However, it has a C-terminal 430 amino acid region with no homology to any known proteins. drgc RNA is expressed at low levels throughout development and in adult heads, and abundantly in adult bodies. In situ hybridizations to adult tissue sections showed that drgc mRNA is expressed in a wide range of tissues, including the optic lobe, central brain, thoracic ganglia, digestive tract, and the oocyte. In addition to the characterization of two GCs, we have also characterized an ERG-defective mutant, ninaF. These studies suggest that the ninaF gene likely encodes an eye-specific protein, B5, which may be a component of the cytoskeleton of the rhabdomeral microvillus in the Drosophila photoreceptors.
Degree
Ph.D.
Advisors
Pak, Purdue University.
Subject Area
Molecular biology|Neurology
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